


Operation: Rescue from the fallen sky.

by AlmaDescompuesta



Category: Katekyou Hitman Reborn!, 僕のヒーローアカデミア | Boku no Hero Academia | My Hero Academia
Genre: Alternate Universe - Canon Divergence, Alternate Universe - Reincarnation, Gen, Past Character Death, Tsuna and Eri are brothers
Language: English
Status: Completed
Published: 2020-07-28
Updated: 2020-07-28
Packaged: 2021-03-06 00:28:56
Rating: Teen And Up Audiences
Warnings: Major Character Death, Rape/Non-Con
Chapters: 1
Words: 2,317
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/25574356
Author URL: https://archiveofourown.org/users/AlmaDescompuesta/pseuds/AlmaDescompuesta
Summary: Rebirth was not the craziest thing that ever happened to him if we count that his mist guardian had died six times.So it shouldn't surprise you that after he passed away on the battlefield, he opened his eyes to a world filled with Quirks and earning a little sister along the way. Only for his mother to abandon them with his grandfather Yakuza and as if it were fate, he is named successor to the eight Precepts of Death until suddenly his grandfather falls into a coma and Chisaki is named new leader to begin his plan to eradicate the quirks of the world, using Tsuna and his sister Eri to do it. Oneshot
Relationships: Chisaki Kai | Overhaul & Eri, Sawada Tsunayoshi & Chisaki Kai, Sawada Tsunayoshi & Eri
Comments: 1
Kudos: 110





	Operation: Rescue from the fallen sky.

**Author's Note:**

> Quick comment, my main language is Spanish and not English, if you don't understand something, you know why.

He knows he was reborn in another world than his own, or at least he was reborn in the very distant future . How do you know?

Easy.

Because he clearly remembers himself as a young man of twenty - four who died on the battlefield against the mafia and because he never had a younger sister.

Not for the first time, he thinks fate hates him.

He quickly learns that the strange mutations and powers in this place are not the dying flames that he knows, but that they are quirks and he is likely to have one as well when they grow up.

If its horn is an indication.

From the chair that helps him to see himself in the mirror, he notices that apart from the evident horn on the left side of his head , his childish appearance is the same as in his previous life. More specifically, when he was Tsunayoshi Sawada Di Vongola .

"If Gokudera-kun were there , he would surely go crazy," he muttered to himself, letting out a dry laugh.

If his storm had run into this world, there is no doubt that he would be jumping with joy when meeting his beloved UMAS, and perhaps he would not stop admiring his new addition.

Quickly stop thinking about your right hand when the pain in your chest becomes excruciating.

For the thousandth time he wonders why I take that bullet for him?

Time passes and he is now six years old and a quirk .

It was discovered by his kindergarten teacher when mistakenly é l agreed without problem two chemical cleaning without react violently when cleaning. With a few tests with his new gift, it was revealed that he can mix substances without risk of repelling.

An example was when they made him mix water with oil, making them both submit without problems. The doctor ironically called it " Harmonization ." It is not very striking, but not modest either.

It takes a while for his little sister to manifest her quirk from an early age.

As a former Mafia Don in his past life, he is used to hearing and even rarely seeing a child hurt or kill one and even both parents when their flames were awakened. It is reasonable that the minor did not know how to control his power the first time it manifested itself, it was not the child's fault.

Too bad his new parent didn't share that idea.

\- A monster! You are a monster! - The recent widow was screaming euphorically. She had seen her husband disappear just by touching her daughter. - You are cursed ! You listened! DAMN! -

The traumatized Eri could only hear her mother cursing her without question.

\- What did I do to make you do this to me ?! You-- wait Tsu- chan! - She exclaimed shocked to notice how her eldest son was approaching his cursed daughter.

Tsuna did not listen to his mother and approached his little sister, who was still together with her late father's clothes and did not need her hyper-intuition to confirm it.

Already in front of his beloved little sister, I do not hesitate to surround him in his arms to hug and comfort her. Sensing the warm arms of the older brother, Eri does not hesitate to start crying.

With her small face plastered to her shoulder as she cried as she sobbed out for her father, Tsuna vows with his dying will that he will protect his little sister from anyone who will harm her .

May God not allow him to experience the agony of losing another little brother again.

Her mother leaves them with her maternal grandfather, although at first she did not want him to stay, she contradicted her that, if Eri had to stay here, he as her older brother would stay with her.

At first she doubts, but in the end she leaves the place without saying goodbye to any of them.

As a former tenth vongola, he soon realizes that his new grandfather's house is actually a yakuza base , speaking of yakuza , it turns out that his grandfather is the current head of the organization.

Just add him an uncle who was adopted by his grandfather and already has a Xanxus .

\- ... How we do not know properly how the quirk of Eri - chan, would you mind examining Chisaki - speak his grandfather interrupting his thoughts.

The man he was talking to was still next to him, who just nodded his head at his father's request.

The old man became aware of the situation and quickly introduced them. - Tsuna-kun , Eri -chan, let me introduce my adoptive son, his name is Chisaki Kai and from today he will be his uncle -

Tsunayoshi just limited himself to seeing his uncle, as if he expected him to suddenly start screaming the trash they are.

Since he didn't speak first, he tried to start a conversation with his uncle.

\- Nice to meet you, Kai-ojisan - I greet the brunet politely along with a shy greeting from his little sister.

He only received an empty look from the man.

Well, at least I don't shoot him. Xanxus always hates being called uncle in Japanese or Italian.

Perhaps he has only lived with his grandfather for a short time, but the lord has earned his respect, clearly this person is a noble yakuza . Since, unlike many power-hungry chiefs, he only seeks a way for the yakuzas to live in peace without being called villains.

He also lived with his subordinates who were devoted to him, clearly he was heaven.

Not realizing that since he thought well of his grandfather, he also had a good impression of his grandson.

All the yakuzas who knew Tsunayoshi could honestly say that this boy was not normal , but with a world where everything was determined by the quirks , it can easily be overlooked.

It was clear that the boy was very mature for his age, sometimes he would inadvertently help his grandfather when he had problems with his organization.

Another point in his favor was his noble heart, even as a grandson of the chief who enjoyed certain privileges and luxuries, the boy usually helps the maids to clean and even talked calmly with other yakuzas to ask them about their day.

All that and more without forgetting to take care of your little sister.

The most veteran believed that his boss would take his grandson as the clan's successor, they had seen the boy's great leadership ability , but before a decision was made about it, his boss went into a coma.

Many accused Chisaki of the health of their boss, it was already known that he shared a twisted idea about how the yakuzas should be and his discontent with Tsunayoshi taking the mantle as head of the eight precepts of death.

But since Tsuna was still too young for such a charge, they had no choice but to allow Chisaki to take control of the organization.

Many things changed the moment Chisaki took power from the Eight Precepts of Death .

Starting with his plan to eliminate quirks in every corner of the world, even if it meant using his beloved father's grandchildren.

At eight years old, Tsuna felt helpless with his situation.

Since Chisaki took control of the yakuzas , both he and Eri have undergone various tests and experiments to achieve the supposed cure for humanity. The quirk of Eri rewinding and quirk of harmonization, Chisaki was sure it would achieve in a short time.

But there were some difficulties in the course, there was the fact that each prototype bullet they manufactured cost beyond the initial budget and that they miscalculated their quirk in the use of manufacturing, although their quirk harmonized with the blood and chemicals that the bullet, he wasn't likely to get it right at first.

To be clearer, its harmonization could increase the effects of completely erasing the quirk, but if you didn't have the correct amount of blood, you could cancel the effect. They just had to find out how much of their cells was needed to get the drug.

So his sections in the lab were longer compared to Eri's , at first he resisted the procedure, but ...

Mukuro had it worse.

They only had to make inquiries while his mist was literally murdered six times in what they experimented with his body to make him more compatible with each path of hell he gained in each death.

If your executioners noticed that you stopped resisting in the following sections, they said nothing.

\- Then the bright sun used its yellow flames against his opponent - Tsuna related to his little sister who was trembling with fear.

The poor girl had been punished after she escaped from her caretaker, causing Chisaki to kill him for his incompetence. She didn't fully know the details, but judging by her killing intent, it was not a good thing.

When he tried to get answers from Eri , she only answered him with warm hands like his.

-… and with one blow he managed to knock down the confused forest - He kept counting the time his Oni- san fought with Aoba-kun on Simon Island .

Thinking of his guardians hurt him so much, he always wondered if they regretted following him when he made the decision to eliminate the mob.

\- They have experienced it first hand - I provoke Overhaul to the young hero, who listened to how Overhaul boasted of having murdered and revived them.

The hero fiercely launched into a fight with the yakuza chief .

In Tsuna's opinion , the fight was impressive. His fighting ability along with his quirk handling was comparable to that of Kyouya and Reborn .

He was so distracted in the fight that he didn't notice how Nemoto was pointing a gun at him and his sister, he only had time to hug his sister to protect her from the shot the instant I heard the characteristic sound of the gun.

All seen by the hero Lemillion .

They were so used to it that they didn't cry or scream, Eri just closed their eyes and clenched their teeth while the older one stood between his sister to receive the damage .

It was there that Lemillion understood that his behavior was adopted after years of abuse, despair, fear and hopelessness, is what he thought.

"I will never let either of you feel these feelings again" Mirio thought with determination, launching himself towards the brothers with a smile. "I won't let them be hurt anymore!"

The next thing he knew, he was shot and felt his quirk disappear .

Only Tsuna could look at Lemillion with pure horror engraved on his face, in which his mind played a trick on him.

For a moment he could visualize his beloved storm instead of the hero, taking the bullet that would take his life.

His younger siblings will be his death, is what his youngest self thought when caring for Lambo along with I-pin and Fuuta .

He shouldn't have excluded Eri from that sentence.

After he disappeared when he was busy helping Lemillion walk after he lost a lot of blood from his fight against Overhaul , he was terrified at the idea of her willingly going back to that man.

He tried to go for it, but his intuition was telling him to leave it to the hero in the green suit, so with remorse he ignored him. It wasn't long when they ran into another hero named Suneater accompanied by the police, it was from there that he ran away before they noticed him to go looking for his little sister.

Running through the shattered corridors with all the force he had, without warning he felt a headache that made him stop.

His hyper intuition was like crazy, sending him danger signs all over the place. From one moment to another he was flying in the sky with large pieces of stones around him, it was right there that he observed that hero in green who was carrying his little sister on his back, giving a strong punch to Chisaki that would make his Oni- san.

Then he understood, the heroes won.

The eight Precepts of Death on his side lost, now Eri was safe. She could live a life as normal as she could and enjoy what remains of her childhood.

It was at that moment that the rest of the heroes and police officers realized that he fell at a high distance, if they did nothing, he would surely die from the blow.

But ... he doesn't care.

He could easily use his flames from heaven to save himself, but he didn't want to continue living with the pain of not having saved his family in his past life.

He would just close his eyes and say goodbye with a smile.

But fate returned to respond with the middle finger to his desire.

\- TSUNA-NII! - Someone was heard screaming from the ground. That voice would recognize her anywhere in the world.

\- Lambo- kun - Susurro impacted the owner recognize the voice.

With a twist of his head he witnessed the new appearance of his lightning keeper. Wearing a leather suit over a cow print shirt accompanied with the characteristic horns on his head.

His beloved little brother who was unjustly murdered at the age of nine, was lying flying to his address thanks to the heroine Ryukyu to save him.

\- Tsuna take my hand! - Lambo exclaimed desperately as he raised his arm to his direction.

How cruel you are Lambo .

Tsuna-nii cannot say no to her beloved little brothers.

Not in his past life, nor in this one.

Everyone saw with relief how the eight-year-old boy who was falling to his death was rescued by young Lambo.

The two were intercepted by Ryukyu , before they hit the ground. But they both didn't care, neither of them could stop crying after meeting again.

At 9:15 am the rescue operation was completed.

**Author's Note:**

> Curiosity that saves # 0
> 
> The fic is completely inspired by “ F or the heroes , a will ” by arurun in Ao3. Although I do not like Bnha due to differences of ideas, I really like reading crossovers of this one with Katekyo hitman reborn .
> 
> A few clarifications, Tsuna still has his flames, but they are too weak since his determination and pride were his friends or family, but in his world as the mob boss he tried to eliminate the corrupt mob with the help of his guardians and allied families like Varia, Giglio Nero, Milliefore , Callavone and also the ancient Arcobalenos . But many famiglias were against it and as a result they rebelled against Vongola and allies.
> 
> As a result, several of his friends ended up dead, being Lambo the first to die of his guardians that caused great pain not only for Tsuna . So over the years all his friends ended up dead for wanting to save him, with Tsuna being the last one to die after he finished killing the last remaining families and then succumbing to his injuries.
> 
> With that trauma before being reborn, it becomes useless to control his flames, until he is reunited with Lambo.


End file.
